Small amounts of iron, copper, manganese, cobalt, magnesium, calcium, and zinc have been determined to be helpful, if not necessary, for plant and animal life. In the course of agriculture, the soil or other growing medium can become depleted of these elements due to plant uptake, and other factors such as erosion, insolubility from combination with other materials in the soil, and/or weathering. Thus, there is a need to replenish these micronutrients so that the growing medium can be reused for new crops. A lack of or a depletion of these micronutrients can create a multitude of problems, including, but not limited to, stunted growth and crop loss. Additionally, livestock animals that feed on grasses and other vegetation that are low in micronutrients do not obtain their full requirement of micronutrients and thereby may suffer poor health and/or slow growth.
Micronutrient replenishment has been handled by the direct bulk addition of metal sulfates to the soil. This method had some drawbacks. First, the majority of the metal sulfate would either run off in the first water application, leach into lower levels of the soil, or the metal would oxidize and have limited bioavailability. Second, in neutral or alkaline soils, for example chalcareous soils, the metal ions would react and precipitate as insoluble, and non-bioavailable, oxides and hydroxides.
Chelates have been developed and provide a means to maintain bioavailability of the micronutrient metals by binding with the coordination sites of the metal ions to maintain their mobility and bioavailability. For example, ethylenediamine tetraacetic acid (“EDTA”) can recruit up to six coordination sites in the form of four carboxylic acid moieties and two amine moieties, thereby forming a cage-like structure that resists any reactivity with oxide or hydroxide ions present in the metal ion's environment. Accordingly, the metal ion can retain its bioavailable state even in the presence of reactive caustic anions until it can contact a root hair and be taken up by the plant.
The manufacture of known metal chelates has traditionally included a process of dissolving a metal salt in a large amount of water, then adding the chelator, and then drying the reaction product until it crystallizes. This process is energy-, water-, and time-intensive.
Accordingly, it is desirable to provide a metal chelated product that creates a metal-chelator network and that may be manufactured by a process that minimizes the amount of water and subsequent drying needed. This manufacturing process can be adapted to produce either granulated chelated micronutrients, which are typically intended to remain in semi-solid form for a period of time in the soil, or micronutrient powders, which typically are intended to dissolve into water quickly and completely.